1. Field of the Invention
The present invention relates to an aligning device for aligning the optical path system of a laser beam machine.
2. Description of the Related Art
In a laser beam machine, the laser beam is transmitted from a laser oscillator to a machining torch, and a mirror so-called a mirror is used to change the transmission direction of the laser beam. In the transmission path (optical path) of the laser beam, the laser beam must be aligned so that it is parallel with the axis of movement of the laser beam machine and also passes the center of the mirror. This alignment operation is called a beam alignment operation.
In the beam alignment operation, since the laser beam is not a visible light, the center of the beam must be confirmed by disposing a cross-shape target at the center of a mirror holder and burning the shadow by the laser beam passing the cross-shape target on a cardboard or a plastic board placed at the rear of the target. This confirmation operation is called a burning operation.
In the beam alignment operation, while moving the axis of the laser beam machine, the center of the laser beam must be confirmed each time via the burning operation to perform alignment so that the laser beam and the machine axis are arranged in parallel and the laser beam is irradiated on the mirror. Since the current alignment method requires the burning to be performed each time the axis is moved, and the burning to be performed each time the mirror is aligned, the conventional beam alignment operation requires an extremely large number of alignment steps.
FIG. 6 is an explanatory view showing the basic structure of a laser beam machine.
The laser beam machine 1 comprises a work table 10 having a work W1 placed thereon. A guide 12 is disposed on both sides of the work table 10, and a carriage 20 is disposed movably in the X-axis direction. On the carriage 20 is disposed a working head 30 capable of moving in the Y-axis direction, and the working head 30 supports the torch 40 so that it moves up and down in the Z-axis direction.
The laser oscillator 50 is fixed to the ground, and the oscillated laser beam LB has its optical axis changed via mirrors M1, M2, M3, M4 and M5 to be supplied to the torch 40.
FIG. 7 is an expansion plan of the mirror arrangement.
Each mirror comprises a holder 60 for supporting the mirror, one pivot 70 and two adjusting screws 71 and 72 for adjusting the mounting angle of the mirror. By rotating the adjusting screws 71 and 72 and adjusting the tilt of the mirror, the optical axis of the laser beam LB can be aligned.
FIGS. 8 and 9 illustrate an aligning method called a burning method.
For example, it shows the method for aligning the optical axis of the laser beam LB transmitted from mirror M2 to mirror M3.
First, the mirror M3 is removed from the holder 60, and a member having a cross-shape pole is attached to a round hole called a cross-shape target 80. Then, a target plate 90 is disposed at the rear portion of the cross-shape target 80. A member such as a plastic board or a cardboard capable of having a burned mark remain thereon when laser beam is irradiated is used as the target plate 90.
When a low-energy laser beam LB is irradiated from the laser oscillator in this state, the laser beam LB passing through the cross-shape target 80 leaves a burned mark (burning) B1 on the target plate 90.
FIGS. 10A, 10B and 10C show the shapes of various burnings B1.
FIG. 10B shows that the optical axis of the laser beam LB traveling from mirror M2 to mirror M3 is at a correct position, and FIGS. 10A and 10C respectively show that the optical axis is displaced.
FIG. 11 shows a method for aligning the optical path axis of the laser beam LB using the burning of the target plate mentioned above.
The operator sets the cross-shape target 80 and the target plate 90, outputs a low-energy laser beam LB from the laser oscillator, visually confirms the burning B1 on the target plate 90, operates the adjusting screws 71 and 72, and generates the burning B1 again. This operation is repeated until the burned mark corresponds to the center of the cross-shape target 80.
In the laser beam machine 1, the carriage 20 and the working head are moved along the X axis and Y axis, so as to subject work K1 and work K2 to laser processing. Thus, the optical length between mirrors M2 and M3 or the optical length between mirrors M3 and M4 are changed constantly.
The operation for aligning the center position of the optical path axis of the laser beam irradiated on the mirror M3 so that it corresponds to the center of the mirror at all the positions on the X axis requires an excessive number of process steps by the method described above.